This invention relates specifically to an appliance leakage current interrupter, commonly known in the industry as an ALCI. Devices of this general type are known in the industry as ground fault interrupters (GFIs).
It has long been recognized that in certain types of small appliances it is desirable that if any ground fault occurs in the device, the flow of current be immediately interrupted to prevent the user from being subject to an electrical shock. For example, certain types of appliances, such as hair dryers, electric shavers, radios, etc., may be used by the owner while he or she is taking a bath. If the appliance should inadvertently fall into the water, in many cases a ground fault or electrical short will occur, causing a severe electrical shock to one who is bathing in the water, which in numerous cases has proven to be fatal. Recognizing the severity of this problem, the Consumer Product Safety Commission has promulgated rulings which are implemented by Underwriters Laboratory to the effect that safety means must be provided to prevent electrical shock if a hair dryer should fall into water with the switch of the hair dryer in its "OFF" position. This ruling, which became effective in or about October of 1987, was based on the premise that most accidents of this type occurred when the hair dryers are not in use, i.e., the operating switch for same was in the "OFF" position, and the hair dryer somehow inadvertently fell into a bathtub or the like. For example, someone taking a bath who intended to use an appliance of this type might position same on the rim of the bathtub and then accidentally knock same into the water, resulting in the possibility of electrical shock. The theory apparently was that when the appliance was in actual use, and the operating switch was in its "ON" position, the appliance was being held by the user and was less likely to accidentally fall into the water. Of course, this did not apply to appliances such as small radios, and furthermore, experience has shown that even when the appliance is being held by the user and is in actual use, there is always the possibility that the appliance will become inadvertently dislodged from the user's grasp and fall into the water.
Thus, Underwriters Laboratories has come out with a further ruling, to be effective Jan. 1, 1991, to the effect that safety means must be provided for hair dryers to prevent electrical shock when the hair dryer falls into water or otherwise suffers a ground fault for any reason, regardless of whether the switch of the hair dryer is "OFF" or "ON".
Under the previous regulations wherein hair dryers were required to be safe only when the hair dryer was in its "OFF" position, double-pole waterproof switches, such as the type of switches shown in U.S. Pat. Nos. 4,652,706 and 4,789,766, satisfactorily resolved the problem and met the then existing regulatory requirements. However, under the new regulations, coming into effect on Jan. 1, 1991, where it is necessary to have a ground fault interrupter operative in response to the presence of any kind of ground fault condition, whether or not the appliance is in its "OFF" or "ON" position, new design and development work has become necessary, and the present invention provides a compact and efficient ground fault interrupter or ALCI that will effectively meet the safety requirements that become effective on Jan. 1, 1991.
Obviously ground fault interrupters are not new in the art, and U.S. Pat. No. 4,719,437 dated Jan. 12, 1988 is exemplary of the type of ground fault interrupters that have heretofore existed, and said patent is thought to represent the closest prior art of which applicants are aware. However, the device shown in U.S. Pat. No. 4,719,437 has certain disadvantages in that it is relatively cumbersome, and more importantly, will not effectively function to interrupt the flow of current if for some reason or somehow outward movement of the reset button is prevented wherein a ground fault may exist.